public class Example {
    String str = new String("good");
    char[] ch = {'a', 'b', 'c'};

    public static void main(String[] args) {
        String s1="abc"+"def";//1
        String s2=new String (s1);//2
        if(s1.equals(s2))//3
            System.out.println(".equals succeeded");//4
        if(s1==s2)//5
            System.out.println("==succeeded");//6


        Example ex= new Example();
        ex.change(ex.str, ex.ch);
        System.out.print(ex.str + " and ");
        System.out.print(ex.ch);
    }

    private void change(String str, char[] ch) {
        str = "test ok";
        ch[0] = 'g';
    }
}
